Users of marijuana and alcohol may be savvier about the health risks posed by these substances than those who abstain, new research suggests.

The findings, which were drawn from a large sample of Swiss men, showed that men who frequently used marijuana, alcohol and tobacco sought out information about the health risks of those substances more than those who didn't use them.

That may be troubling news for anti-substance-abuse campaigns, which often rely on scare tactics highlighting the health risks of drugs, according to the study, published July 11 in the International Journal of Public Health.

The study shows that "when you know a lot about the risks and everything about the substances, it doesn't really bring you to consume less," said study co-author Petra Dermota, a psychologist at the University of Zurich. "You even consume more."

Drug knowledge

Scary images of smokers' lungs or scarred livers are mainstays of anti-smoking and anti-alcohol campaigns. But research hadn't shown that such health information actually reduced people's drug usage. [Trippy Tales: The History of 8 Hallucinogens]

To see whether health information dissuaded people from using drugs, Dermota and her colleagues surveyed 12,000 men around age 20 who were entering the Swiss Army. Because the Swiss have universal, mandatory military service, the sample represents a cross-section that is representative of the young Swiss male population, she said.

The survey included questions about use of marijuana, alcohol and tobacco. In addition, the researchers asked the men how often they sought information on the health risks of those substances and how knowledgeable they were about those risks.

People who smoked cannabis at least once a week were four times more likely to search for health-risk information as those who abstained.

Regular smokers and those who binge drank (consumed at least five drinks in a single sitting) at least once a month were also twice as likely to search for information about the health risks of alcohol or tobacco.

The regular substance users were also more likely to rate their own knowledge of the health risks higher than those who abstained. That was surprising, the researchers said, because the drug and alcohol users in the study tended to be less educated, and less-educated people generally tend to rate themselves as less health savvy.

Not a deterrent

The findings suggest that substance-abuse prevention campaigns may need to be tweaked. It may be that the long-term consequences, such as lung cancer or cirrhosis of the liver, are simply too far away to have much of an impact on people's immediate decisions, Dermota said. Or, it may be that drug users believe the alcohol or marijuana's benefits outweigh the risks.

Instead, anti-drug messages should be more interactive, and spur critical thinking about the drugs to change people's attitudes about drug use, Dermota said.

"At the moment, most campaigns are just giving young people a lot of information, but this is not enough to prevent people from being at risk and using drugs," Dermota told LiveScience.

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Tia Ghose

Tia has interned at Science News, Wired.com, and the Milwaukee Journal Sentinel and has written for the Center for Investigative Reporting, Scientific American, and ScienceNow. She has a master's degree in bioengineering from the University of Washington and a graduate certificate in science writing from the University of California Santa Cruz.